The present invention is directed to bicycles and, more particularly, to a bicycle derailleur with a structure that inhibits misalignment of a drive mechanism relative to first and second base members.
Bicycles are used for general transportation as well as for sports and recreation. Such potential uses have resulted in the development of bicycles that are comfortable to ride under a variety of riding conditions and are suitable for a wide variety of riding purposes. Not surprisingly, bicycles that have some provision for the automation of various components to accommodate a particular riding environment have become very popular.
Most bicycles currently have transmissions that allow the rider to select a suitable gear ratio from among a plurality of available gear ratios as the riding conditions change. Such transmissions may include a derailleur that is detachably secured to the rear end of the bicycle frame and is used to engage a chain with one of a plurality of sprockets that are mounted on the hub axle of the rear wheel. Conventional rear derailleurs comprise a base member mounted on the rear end of the bicycle frame, a four-point link mechanism mounted to the base member, and a chain guide mounted to the four-point link mechanism. During operation of the rear derailleur, the four-point link mechanism moves the chain guide in the direction of the hub axle, and the chain guide switches the chain to a desired one of the plurality of sprockets.
Recently developed rear derailleurs include a drive mechanism, such as a rotating motor, housed within the base member. More specifically, the base member may comprise a plurality of members that form a housing space, and the drive mechanism may be disposed within the housing space. The four-point link mechanism is controlled by this drive mechanism, thus allowing the rear derailleur to be more easily operated in both automatic and manual shifting modes.
When such conventional bicycle drive mechanisms are mounted on the rear derailleur, the plurality of base members can become misaligned with each other due to impacts on the base member caused by falls as well as by vibrations and shocks caused by changes in the surface of the road. This also causes the drive mechanism to become misaligned in the housing space between the base members, thus adversely affecting the ability of the derailleur to precisely shift the chain from one sprocket to another.